I've been using a cassette deck again for the past few months and would like to play my tapes in a couple portables I've got.

I was wondering what a good test signal is, something that will make it real easy to set azimuth by ear using just a tape with that signal and a screwdriver, as I've got no other equipment.

I find that I'm not particularly sensitive to small variations in steady tones, otherwise I'd just use a 10 kHz tone from a test tape. I've also tried using music with lots of HF content but I can never be sure if I've nailed it.